Modern integrated circuits (ICs) often include a relatively large number of transistors and building blocks. As a result, designers and manufacturers continue to seek ways to reduce the design cycle times of the ICs. As one way of doing so, designers increasingly use digital circuitry to accomplish the tasks once reserved for analog circuits.
Nevertheless, some analog circuitry continues to remain on ICs. It becomes harder to maintain the analog circuitry as the migration with the scaling of digital circuits continues, because of relative mismatches. Furthermore, because of their nature, the analog circuitry, and some of the digital circuitry, use reference sources, for example, as a source of bias signals, etc.